It is known to use deployable side curtains in automotive vehicles to protect vehicle occupants during side impact and/or rollover events. Such side curtains, also commonly known as rollover curtains, may take the form of a flexible curtain (usually made of a mesh material) covering the side windows to protect against the occupants being ejected through the doors or windows, or an inflatable airbag which protects against ejection and also provides a degree of cushioning.
Prior to deployment, a side curtain is typically folded or rolled into a compact, elongated shape that is secured to the vehicle adjacent the roof rail above a window opening or door opening. Interior trim panels cover the stowed curtain to hide it from view. In the deployed condition, the side curtain extends downwardly from the roof rail to at least partially cover the window/door openings and/or the pillars adjacent the openings. One or more curtains may be disposed along the length of the passenger compartment as necessary to provide protection to occupants in any or all of the rows of seats in the passenger compartment. U.S. Pat. No. 6,000,715 teaches a non-inflatable side curtain. U.S. Pat. No. 5,540,459 teaches inflatable an inflatable side curtain. U.S. Pat. No. 5,788,270 teaches a side curtain comprising both inflatable and non-inflatable sections.
During a vehicle rollover or other type of side impact event, the side curtain should move from its stowed condition to its deployed condition rapidly and the lower edge of the curtain should be held close to the side of the vehicle during deployment in order to ensure that the curtain passes between the occupant and the side wall of the vehicle before any part of the occupant's body moves outboard of the curtain. It is known to attempt to keep the curtain close to the vehicle side wall by means of tethers, cords, or similar members connecting the forward and/or the rear lower corners of the curtain to the vehicle structure when in the deployed condition.
For some curtain configurations, however, it may be desirable to connect the curtain to the vehicle structure at some point on the lower edge of curtain lying between the forward and rear corners. For example, when a restraint curtain extends along two or more rows of occupant seating, connecting the midpoint of the curtain to the adjacent B-pillar or other structure may improve the deployment dynamics and post-deployment stability of the curtain.
U.S. Pat. No. 5,788,270 teaches a curtain having a tab at the midpoint of its lower edge, the tab engaging a channel extending generally vertically along the B-pillar of the vehicle. The tab is urged downward along the channel as the curtain deploys, with the engagement between the tab and the channel holding the lower edge of the curtain closely adjacent the B-pillar throughout its deployment. This configuration requires that the curtain be folded such that, when in the stowed condition, its lower edge is exposed on the outside of the folded curtain and immediately adjacent to the channel so that the tab may be connected with the channel.
To ensure proper deployment, however, a curtain is often folded or rolled inwardly on itself so that the lower edge is buried in the interior of the stowed curtain. For example, in some circumstances optimum curtain deployment is achieved by placing the curtain in the stowed condition using a "roll fold" in which the curtain, starting at the lower edge, is rolled upwardly in a spiral fashion toward the upper edge. When a curtain is folded in this manner, the lower edge of the curtain cannot be connected directly to the vehicle structure as taught by the '270 patent. While it is possible to attach a tether to the curtain at a midpoint of the lower edge and simply roll the tether up into the curtain, this requires the tether to be longer than the vertical dimension of the curtain. A tether this long would have to tightened by some mechanical actuator during deployment of the curtain, with resulting increases in the complexity, cost, and deployment time of the restraint system.